Definición de tertium quid en inglés:

sustantivo

Unfortunately, given the interminability of the debate, only a few voices in the book seek to find a tertium quid - that is, a wider outlook that could lift the debate off its current hinges and onto a more illuminative level.

Unable to fully reconcile the cases, Justice Scalia said that the trade dress in Two Pesos was either some form of packaging, or tertium quid.

Origen

Early 18th century: from late Latin, translation of Greek triton ti 'some third thing'.